Arrangement for carrying off heat



E. PFIFFNER ARRANGEMENT FOR CARRYING OFF HEAT Filed May 5. 1924 Patented Oct. 5, 1926.

EMIL PFIFFNER, OFKBUIAPEST, HUNGARY.

ARRANGEMET FOR CARRYING OFF HEAT.

l Application led. May 5, 1924-y Serial No. 711,249, and in Germany April 3, 1923.

It is already known to insulate the hightension coils of transformers and the like by means of infusion in an insulating material in place of the generally used oil insulation.

In the solid condition the known insulating infusion materials possess a vconsiderably better insulating power or property Ithan the transformer-oils and therefore render possible smaller insulation distances and smaller dimensions of the coil or of the transformer.

However compared with the above, the infusion materials are disadvantageous, as a smaller conduction of heat` is obtained and the danger'of a local excessive heating is present, which may cause a destruction of the insulation of the coils.

The construction according to the present invention has for its object to remove this draw back and put on an equal footing the insulation by infusion material, with the insulation by oil.

The essential feature of the arrangement according to the present invention consists in employing the infusion material solely for the electric insulation, but to arrange good conducting heat-channels or ways for the carrying oil of heat. Good heat conducting members generally also are conductors of electricity. In order that the electric insulation may not be affected due to the provision of these heat-channels, the latter should be arranged as far as possible in the equipotential surfaces of the electric field.

The arrangement is the most simple in case the transformer or the coilis disposed within an insulating casing, as in this case the equipotential surfaces transect the shell of the casing and the heat-channels or ways may pass up to the shell of the casing.

One mode of carrying out the present invention is illustrated by way of example on the accompanying sheetl of drawings in which: l

Fig. 1 shows a coil provided with the ar rangement according to the present invention in sectional elevation, and

Fig. 2 is a cross-sectional view of the conf struction illustrated in Fig. 1.

Fig. 3 is a detail view in sectional elevation and on an enlarged scale.r

In Figures 1 and 2, a system of high-tension coils, comprising an iron core lc and a number of coils s1, s2, s3, s4, 85 which are connected in series, is encased in an insulating casing z.

The equipotential surfaces of the electric field are disposed essentially vertical with respect to the axis of the coils. Plates Z of agood heat-conducting material, for instance copper, are disposed between the individual coils si, s2 and so forth, in order to carry olf the heat generated in the coil yto the shell of the insulating casing. The heatconductivity of copper is for instance 1000 to 2000 times larger than that of the infusion material m, which may consist for example of asphalt, paratlin and the like. Thus i the thickness of the plates Z is about one twentieth ofthe distance between two plates, which place is illed with the material m, the arrangement will improve the conduction of heat to 100 times, e. g. the conduction of heat is nearly exclusively carried out by the vplates Z while the. infusion material solely serves for the insulation between the surfaces of a like potential in the fielddirection.

The equipotential surface of the iron-core may be increased'by providing wings or extensions h on the clamps for the core to carry off the heat generated inthe iron-core and for improving the carrying oil of heat and the passage of the heat to the shell of the casing.

The invention is not limited to apparatus with an insulating casing, but in the latter case the heat channels or ways may be arranged without any diiliculty. In order to provide these channels or Ways it is however necessary, that the eouipotential surfaces of the electric field pass into a ventilated outside space.

As illustrated in Fig. 3 the heatconduct ing plates may be provided with an enlarged rim or border r, in order to reduce the contact fall at the shell of the casing.

1. An arrangement for carryingtoi heat in an electric device, comprising in combination a casing containing a cast insulating material which has electric and thermal insula'ting properties, a system of coils arranged in the casing and embedded in said material, and plates having high heat-conducting properties disposed in said material in such manner, that the plates are arranged 5 as far as possible in the equipotential surfaces of the electric field.

2. An arrangement as claimed in claim 1 in which the casing is formed of insulating material and the plates extend into close proximity to the inner surface of said cas- 10 mg.

In testimony whereof I hereunto affix EMIL PFIFFNER. 

